Hi all, we have some cracks and nail pops around our return air grill on the ceiling and a building and pest inspection report said this was due to an unsupported plenum in the roof. How can I easily support this to the joist without compromising the plenum too much? I was thinking of installing 90x45 noggins across the roof joists on both sides of the plenum (60cm) to butt up against the plenum (red lines). Then from here, put in 2 hex screws from inside the plenum and into the timber. Does this sound feasible or a bad idea? I want to simple provide some support for the plenum box which is about around 70 x 35cm and maybe 20cm high. Thereafter I would like to add screws into the ceiling into the joists around the nail pops. Thanks!
Hi @snipwhip,
If the manufacturer can be identified, I would recommend first reaching out to them to see if there is a particular way the unit was designed to be installed or supported.
Otherwise, yes, that sounds entirely reasonable. Installing 90x45 noggins between the ceiling joists on either side of the plenum and then fixing the plenum back to the timber with screws should provide some additional support and help reduce movement. Just be careful not to overtighten the fixings or distort the plenum box.
When repairing the ceiling, I'd also recommend using plasterboard screws rather than simply renailing the affected areas. Screws provide a much more secure fixing and are less likely to work loose again in the future.
If the plasterboard has dropped noticeably away from the joists, it's worth applying some stud adhesive between the back of the plasterboard and the joist before screwing it back up. This will help restore the bond and provide better long-term support.
As always, take care when working in ceiling spaces. Watch your footing, avoid stepping on the plasterboard, be mindful of electrical wiring and insulation, and ensure you have adequate lighting. If you're not confident working in the roof space or assessing the existing support, it's a good idea to engage a qualified professional for assistance.
Please let me know if you have any questions.
Mitchell
Hi @snipwhip
That looks like a fairly recent install, have you considered getting the installers (or builders) back to rectify this? You shouldn't have to fix issues caused by someone elses poor installation work!
Thanks @R4addZ @MitchellMc. It's definitely not recent though I couldn't tell you when it was installed as we bought the house a year ago. If I were to secure it to the noggins, will screwing through the sheet metal of the plenum body (and that yellow insulation around the box) into the noggin cause any leakage issue or it shouldn't really be a concern? If so, how will I deal with that? Thank you.
I wouldn't have thought so, @snipwhip. The screw will seal relatively well and you can just pop some silicone sealant over the screw head to seal it completely.
